Configure in-memory storage

By default, in-memory storage is used if no other storage configuration is provided. With in-memory storage, in place of a relational database, in-memory data structures store the data. A consequence of this is that all data is lost when the node is stopped.

This example shows explicit in-memory configuration for a Sequencer, Mediator, and Participant Node:

# Configures sequencer1, mediator1, and participant1 to use in-memory storage.
canton {
  sequencers.sequencer1.storage.type = memory
  mediators.mediator1.storage.type = memory
  participants.participant1.storage.type = memory
}

Configure H2 storage

This example shows H2 storage configuration for a Sequencer, Mediator, and Participant Node:

# Configures sequencer1, mediator1, and participant1 to use file based H2 storage.
canton {
  sequencers.sequencer1.storage {
    type = h2
    config.url = "jdbc:h2:file:./data/sequencer1;MODE=PostgreSQL;LOCK_TIMEOUT=10000;DB_CLOSE_DELAY=-1"
  }
  mediators.mediator1.storage {
    type = h2
    config.url = "jdbc:h2:file:./data/mediator1;MODE=PostgreSQL;LOCK_TIMEOUT=10000;DB_CLOSE_DELAY=-1"
  }
  participants.participant1.storage {
    type = h2
    config.url = "jdbc:h2:file:./data/participant1;MODE=PostgreSQL;LOCK_TIMEOUT=10000;DB_CLOSE_DELAY=-1"
  }
}

The jdbc: prefixed url can be configured in many ways. The example above configures:

On canton startup embedded H2 databases will be created in the ./data directory relative to the Canton node’s working directory and will have the file suffix .mv.db. When using H2 embedded connection mode only a single process can access the database at a time, so to inspect the database, it will be necessary to stop Canton first. Once no other process is accessing the database, it can be inspected using the H2 tools, such as the H2 Console.

This is essential as the SQL dialect used by Canton is PostgreSQL. This setting enables PostgreSQL compatibility mode.

This gives a thread 10 seconds to acquire a database lock before timing out.

This setting keeps the database open until the Canton process terminates.